6922 Tube Question

ECC88/6dj8 and E88CC/6922 have different maximum current specs with the latter being able to withstand higher levels.

Probably best to ask the designer/manufacturer as to what will "last well/longer" in a specific unit, and if this is not possible then perhaps confer with a reputable tube dealer and/or a forum with knowledgable experts (diyaudio?) who may be able to offer advice.

Think there may be a few exceptions (regarding longevity) like early Telefunken CCA's (a 6dj8 as I understand it), but I may be wrong on this.

In addition there is also the E188CC/7308 that is said to be even more durable (in higher current circuits) than the  E88CC/6922, but I'm too lazy to look up the spec's on all the, above mentioned, versions.

In the Audion/Consonance gear I've owned/used I was able to use 6dj8's in place of the specified 6922's without premature failure, but in a friends Audible Illusions preamp I ended up using extremely durable Russian 6n23-EV's and Telefunken 7dj8's (phono section) which lasted for many years (wasted/trashed some old production 6dj8's and 6922's experimenting, but I had gobs on hand @ that time).

Neither of us liked the sound of old production 7308's in the pre, so those were spared the long term test (ended up selling many of them here on A'Gon and on Ebay).

DeKay

6FQ7 for me.

I don’t think that you should have much of a problem finding 6922s or 6DJ8s. I see that Cary Audio is selling Amperex Bugle Boys 6DJ8s for $80 each.

(On edit: I am not affiliated w/ Cary Audio except as a past customer.)

https://www.caryaudio.com/vacuum-tubes-and-accessories/

Another option (which I now see was already mentioned by @dekay ) that someone turned me on to a couple of years ago that you might consider is the Voskhod 6N23. It’s a Soviet era tube; I am actually running a couple in the front of my 6922 Cary V12 right now.

Yes the 6CG7 family is a wonderful tube type. Got to be careful if you are not using it as a driver however. I would never put a 6CG7/6FQ7 in a highly sensitive application. Same for 12BH7s,

In addition there is also the E188CC/7308 that is said to be even more durable (in higher current circuits) than the  E88CC/6922, but I'm too lazy to look up the spec's on all the, above mentioned, versions.

The 6922 is considered a premium tube vs. the 6DJ8. It has a more rugged build quality and meets military demands. To my ears, they sound the same for a given brand.

The 7308 is truly a premium tube and has different sonics than the other variants. IME with the help of Brent Jessee, we tried 6922 US Amperex and Amperex Holland in my new DAC, the US having more detail and extension, neither had enough low-end punch. I next tried the Amperex PQ Holland 7308. The price was quite a bit higher due to rarity, but this tube had everything I was looking for. The heater of a 7308 draws 7 volts while the 6DJ8/6922 draws 6.3V, but is a drop-in replacement. Both the 6922 and 7308 are capable of lasting 10,000 hours.